Plasma Proteomics and Lipid Profiles Analysis in Patients Affected by Coronary Artery Disease: Focus on Apolipoprotein C-III

Background: In the last decade Apolipoprotein C-III (Apo C-III) has been demonstrated to be a prognostic marker for cardiovascular risk on the basis of the strong correlation between Apo C-III plasma levels and high serum concentrations of triglyceride in humans. In such perspective, the molecular structure of Apo C-III may be relevant for its role Overall, very few studies tried to elucidate the impact of the Apo C-III concentration and modifications (sialylation) on lipoproteins and lipid metabolism and how Apo C-III can affect the outcome associated to Coronary Artery Disease (CAD) parameters. Methods: Three different groups of CAD patients, carefully selected among subjects enrolled in the Verona Heart Study project, were studied by means of proteomics and lipidomics technologies. Isoelectrofocusing and shotgun topdown MS approach were applied for the identification and quantification of the three different Apo C-III glycoforms. Mono and bidimensional western immunoblotting were performed in order to validate protein previously found by comparative analysis differentially expressed according to Apo CIII levels. A total proteomic profile of CAD patients was obtained by SWATH, an untargeted approach, analysis. Gas-Chromatography and Liquid-Chromatography-MS analysis allowed a lipidomic characterization of CAD and CAD free patients. Results: The three Apo C-III glycoforms showed a peculiar trend, where the non-sialylated form presented a negative correlation with the others parameters, instead the monosialylated a positive one. No correlations with the disialylated glycoforms were found. The validation analysis confirmed the comparative analysis results. The SWATH analysis underlined a peculiar set of proteins associated with low and high Apo C-III levels. The lipidomic approach underlined how according to Apo E levels in CAD and CAD free patients it is possible to observe a peculiar lipid profile, in particular high levels of Apo E are associated with the presence of cholesteryl ester oxidized. Conclusion: In spite of the relatively small sample size, the study allowed a multifaceted characterization of Apo C-III and Apo C-III glycoforms distribution in CAD patients. SWATH analysis revealed a set of proteins characterizing patients with high and low levels of Apo C-III. The lipidomic approach underlined that not only the apolipoproteins distribution and common lipids parameters but also some peculiar lipid species may play an important role in CAD. To validate the present results, further analysis are however required, possibly on larger populations of patients .